基于FLAC3D的复合煤岩受载破裂数值模拟及试验研究

采用FLAC~(3D)对复合煤岩模型的单轴压缩破裂进行数值模拟及试验,研究复合煤岩受载破裂应力与应变关系变化规律。针对煤样厚度、复合煤岩组合比、煤层参数、顶底板岩性等参数,对复合煤岩模型进行加载仿真研究,仿真及试验结果表明:单一煤样模型随着高度的减小,应力应变曲线整体阶段存在尺寸效应;改变煤岩组合比例时,其抗压强度基本不变,随煤样比例增大,复合煤岩的整体弹性模量减小,整体刚度减小;单一改变复合煤岩的煤样参数时,随煤样弹性模量增大,复合煤岩的弹性模量越强,应力应变曲线峰值点越高,对应应变越小;单一改变顶底板岩性,对复合煤岩模型的应力应变曲线影响不大。试验结果和仿真结果变化趋势一致,表明所建模型具有一定正确性和适用性。

Numerical simulation by using FLAC3D and experiment of composite coal rock in fracture under load

The paper is to devote itself to presenting a numerical simulation and experiment with the composite coal rock in fracture under the load pressure.The numerical simulation model we have developed is composed of the coal rock complicated mixture with the evenly mixed roof rock,coal,and the floor rock in FLAC3D,which is intended for the exploration of the coal rocks in the process of high compression and then getting to be fractured in the uni-axial loading direction.All the parameters of the said simulated research models concerning the coal rock have been drawn and well prepared in Datong coal mine company.What is more,we have also established a 3-D numerical model (100 mm high and 50 mm in diameter) in hoping to do the experimental and simulated tests to identify and determine the correlation and variety regulations of the stress and strain of the composite coal rock in fracture under great load in different conditions,such as the different coal-seam thicknesses,the different composite ratios,the different coal seam parameters,different roof and floor lithology parameters,etc.The results of our simulated tests show that:(1) The greater the coal-seam height of the model becomes,the faster the stress-strain curve as the result of the peak declining will be,and in turn the steeper the slope would become.In so doing,the characteristic features of the models tend to show somewhat brittle and strain-softened.Moreover,when the height of the model is getting lowered,the curve after the peak declining would become slower,with its characteristic features becoming firm,though its size effect remaining overall even in the stage of fracture.(2) When the composite samples are changing at a ratio among 1∶ 0.5∶ 1;1∶ 1∶1 and 1∶2∶ 1,their compressive strength may not be changing so much.Therefore,with the increase of the proportion of the coal,its overall elastic modulus and stiffness would tend all to get decreased.And,(3)when the coal increases its elastic modulus in its own particularly changing manner,the elastic modulus of the entire model may tend to increase,too.Thus,the higher the stress-strain curve peak point,the less the corresponding strain will be.On the other hand,(4) when the lithological features of the roof and the floor are changing independently,the stress-strain curve may not be changing so much.Therefore,the results of our experiments and our simulation may not be totally consistent,which indicate that the models are basically correct and prove to be worthy of popular application.